Vitamin D is a steroid prohormone synthesized in the skin following ultraviolet exposure and also achieved through supplemental or dietary intake. While there is strong evidence for its role in maintaining bone and muscle health, there has been recent debate regarding the role of vitamin D deficiency in hypertension based on conflicting epidemiological evidence. Thus, we conducted a scoping systematic literature review and meta-analysis of all observational studies published up to early 2014 in order to map trends in the evidence of this association.

Associations between documented sun-exposure, exercise patterns and fish and supplement intake and 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were investigated in a random household survey of Macau residents (aged 18–93). Blood samples (566) taken in summer were analyzed for 25OHD and PTH.

Despite recent downward trends in cardiovascular disease(CVD) mortality rates, CVD deaths still represent 50% of noncommunicable disease deaths worldwide, and there has been an exponential increase in CVD incidence in lowerand middle-income countries. In China, one-third of all deaths were due to CVD in 2005, with numbers anticipated to increase by 50% by 2025, compared with 15% for economically developed countries.

Chinese populations are known to be at risk for vitamin D deficiency, with some evidence that this is due to lack of exposure to sunlight. Vitamin D deficiency and/or low sun exposure have been associated with higher incidence of hypertension in Caucasians. Thus, we investigated these associations in a Chinese population with a high rate of hypertension.